1. Field of the Invention
The present invention relates generally to construction of an outdoor equipment cabinet and, more particularly, to a cabinet for containing electrical equipment components and which is designed to effectively dissipate heat generated by the components during operation.
2. Description of the Related Art
Many forms of electronic equipment, of necessity, must be located in an outdoor environment. Such equipment in typical form may be telecommunications and cable television equipment including active electronic and optical systems and passive cross-connect and splicing fields. It is essential that such equipment be protected from a wide range of ambient temperatures and inclement climatic conditions such as rain, snow, sleet, high winds, ice, and sand storms as well as other in situ environmental issues like seismic vibration, etc. To this end, cabinet enclosures have been developed to house such electronic equipment in a highly weather tight manner.
The type of electronic equipment that is typically housed in an outdoor cabinet enclosure is known to generate considerable amounts of heat in operation. Further, in many environments the ambient air can become very warm and heat up the air internal to the cabinet. This can have a deleterious effect on the electronic equipment and severely limit its effective life. Air conditioning systems and thermoelectric coolers, for example, are known that may be used in conjunction with outside equipment cabinets to aid in maintaining an acceptable temperature within the cabinet enclosure. However, such systems may not be cost-effective for all applications. An alternative approach is disclosed in U.S. Pat. No. 5,570,740 issued to Flores et al., which teaches a built-in cooling system for an enclosure. The Flores et al. cooling system utilizes a combination of a heat exchanger and a plenum to provide for both "internal air" and "external air." The heat exchanger is constructed to include a serpentine internal structure to maintain separation between the air flows. The external air enters at the bottom of the exchanger and flows upward and through the plenum. The internal air enters at the top of the exchanger and is pulled downward through a fan located near the bottom of the heat exchanger. The heat exchanger allows for considerable heat exchange between the relatively cool upward external air flow and the relatively warm downward internal air flow.
While the Flores et al. construction is effective in maintaining reduced temperature within electronic equipment cabinets, the heat exchanger unit disclosed therein is of somewhat of a complicated design that may not be suitable for many applications. Thus, simplified heat exchanger constructions have been proposed, such as that disclosed in Mistry et al., U.S. Pat. No. 5,832,988. Mistry et al. propose a nested columnar heat exchanger comprising an internal air flow column that receives outside air flow and a surrounding air flow column that functions to circulate and cool interior air. The Mistry et al. disclosure further contemplates the use of an adjustable diversion means that switches between two sources of external air, one source which functions to cool batteries contained within the cabinet.
While known apparatus for cooling air internal to an electronic equipment cabinet provides for a degree of effectiveness in serving a cooling function, it is desirable to provide a still improved means for cooling which is yet simpler and more cost-effective to construct. Further, it is desirable to provide such a means which can be used to cool batteries in an equipment cabinet without any moving parts. Still further, it is desirable to provide such a means which serves an additional function of positively locating batteries in a cabinet and retaining them against such occurrences as seismic events or other cabinet vibration. Yet further, it is desirable to provide for natural venting of gases generated by associated batteries without reliance on fans.